Welcome to Seabed Habitats- The newest blog about everything to do with marine habitats.The marine realm is such a dynamic system and is very much an “unexplored wilderness.” Being a relatively new science (with most sub-disciplines being only 50-120 years old), a lot of work is being done to gain a thorough understanding. With technological advances happening rapidly, there are always new methods to try out and new equipment to test. With research being so interdisciplinary in nature, spanning a range of areas such as marine ecology, marine geology, coastal processes, geophysics, oceanography, hydrography, remote sensing, surveying, GIS.. This blog attempts to keep you up to date on the latest developments in the field. From new research ideas to images to the latest technology- all can be discussed here.
Click the maerl to learn more about our planned marine science documentary about maerl beds. This rare & diverse seabed habitat of great conservation significance is little documented.
Emily’s Pinnacles are impressive hard coral formations found in Bermuda and provide the building blocks for the reef. Darwin classified three main types of reefs – barrier reefs, fringing reefs and atolls, with others being patch reef and pinnacle reefs. A pinnacle reef occur when a patch reef occurs at an open shelf, rather than at an atoll.
Here, Google have partnered with The Catlin Seaview Survey, a major scientific study of the world’s reefs, to make these amazing images available to millions of people through the Street View feature of Google Maps. The Catlin Seaview Survey used a specially designed underwater camera, the SVII, to capture these photos. For further views please see the Google Street view Ocean gallery. For more information about the Catlin Seaview Survey please view their website. Explore it here, with brain corals below:
Brain coral is a common name given to corals in the family Faviidae so called due to their generally spheroid shape and grooved surface which resembles a brain. Each head of coral is formed by a colony of genetically identical polyps which secrete a hard skeleton of calcium carbonate; this makes them important coral reef builders like other stony corals in the order Scleractinia. The corals reefs of Bermuda have been especially vulnerable to coral bleaching. Bleaching occurs when the conditions necessary to sustain the coral’s zooxanthellae cannot be maintained and is a generalized stress response of corals.
Morelock J, 2005, Reef Types, Personal Webpage
More on pinnacle reef formation near patch reefs and mounds can be found here: SEPM Strata: Carbonate Facies
Multibeam backscatter is the reflectivity measurement, where as the sidescan sonar imagery is the actual intensity of the return signal. The Sidescan sonar towing configuration provides greater maneuverability, as the depth of the tow-fish above the seafloor can be adjusted, in view of the swath width. For example, the sidescan imagery is less prone to be affected by the slope of the seafloor as it can be positioned, where as the multibeam can only receive the backscatter intensity as it reaches the survey vessel.
The footprint size at the outer beam of the sidescan sonar is larger than at the nadir beam as slant range is greater in the far range; subsequently increasing the two way travel time of the acoustic signal. A larger footprint has a greater uncertainty of detecting the first return, as well as a lower resolution. Hence, the theoretical maximum speed at which the survey vessel should go can be calculated, to ensure not only 100% coverage of the along track beam footprint, but also optimize the footprint size for all the beams. Therefore speed is an important factor to consider when planning a survey.
Thus practically, gaps in the multibeam data sets are present if the survey speed is too fast, as the vessel would have moved away before the acoustic return can reach the receiver. On the other hand, multibeam surveying uses expensive resources, such as ship fuel and a very slow survey speed would use the resources with a limited efficiency, resulting in a smaller area ensonified in the survey. Additional effects are also present for the sidescan sonar as the system comprises of a towed fish. Slow speeds may result in the fish having a decreased momentum/tension in the cable, changing the position of the fish relative to the vessel.
The difference between multibeam positioning and the sidescan sonar positioning is that the sidescan towed fish is found behind the ship, and hence this needs to be corrected for, in relation to the on board DGPS navigation system. This can be done most simply by doing trigonometric calculations, based on the length of the cable out (lay back) and the depth of the fish above the seafloor, as well as accounting for the heading. Base line acoustic positioning systems may also be used, with an acoustic signal being sent by the fish to the vessel, or by triangulation with transducers being based on the seafloor. Similarly the position of the multibeam transducer and receiver on the vessel also needs to be added to a vessel configuration file during processing. Furthermore, a time-lag correction needs to be applied, ensuring the correct position is recorded, with synchronized times of the navigation and the satellite.
If a survey was taken at another time of the year then different weather conditions affecting the movement of the survey vessel in the x,y and z directions would be recorded in the raw data acquired. Hence, attitude sensors on the vessel need to be used to correct the data to different types of movement, or the roll, pitch, heave and yaw. The pitch is a measure of the rotation of the survey vessel in the x axis; the roll is the rotation in the y axis and heave in the z axis. The yaw is the offset between the survey lines. A consequence of more turbulent weather conditions, which has a greater impact on the sidescan system, is the increased presence of air bubbles. This affects the way sound propagates in the surface mixed layer and hence can cause artefacts in the data. Bubbles may also originate from the propellers of other vessels which may be present at other times of survey.
The sea floor composition and the angle of incidence primarily cause variation in backscatter intensity, according to Lambert’s law. The roughness and hardness or acoustic impedance of the sea floor are two key parameters which vary with geological and biological characteristics. These parameters have varying contributions to the backscatter intensity, depending on the angle of incidence. Hence the energy of the ping which is reflected or absorbed is affected by the sediment geotechnical properties, as well as by the grazing angle. Additionally, scattering by targets (e.g. fish, zooplankton, submarines) in the water column can alter the backscatter intensity. Other factors to consider affecting the strength of the backscatter are the depth of the water column and the initial energy of the acoustic signal, as transmission loss occurs in the water column. Here is an example of multibeam backscatter acquired using Reson 7125 system.
Giant kelp forests off of south-eastern Tasmania. Forest locations were Fortescue Bay and Munro Bight. As of January 2013, the forest at Fortescue no longer exists. Reasons attributed to the decline of this kelp forest and numerous others along the east coast of Tasmania include: warming waters, increasing occurrence of invasive species and a disruption of the natural food chain due to overfishing. This video is a tribute to the beauty of these forests in the hope that the attention they are finally getting from the government is not too late to prevent their extinction.
Following a long, and at times difficult, period of consultation and development, the United Nations Secretary General’s Special Representative on the issue of human rights and transnational corporations and other business enterprises, Professor John Ruggie, has produced his final report on Guiding Principles for Business and Human Rights. This is a significant landmark and should cause all businesses whose activities have a real or potential impact on human rights to sit up and take notice.
Professor Ruggie started his work in 2005 and put forward his draft “Protect, Respect and Remedy” framework in 2008; which was unanimously accepted by the UN Human Rights Council and has been adopted by a range of public and private actors since. Three main principles:
- Protect – the State duty to protect against human rights abuses by third parties, including business, through appropriate policies, regulation, and adjudication
- Respect – the corporate responsibility to respect human rights, which means to act with due diligence to avoid infringing the rights of others and to address adverse impacts that occur; and
- Remedy – both State and business responsibility to provide greater access by victims to effective remedy, both judicial and non-judicial.
An article published in the Guardian asks the question “Business and human rights: does reality match the rhetoric? Companies say they support human rights but a new sustainability report suggests that few have detailed policies”
While the relationship between business and human rights will always be a journey, not a destination, for many companies it seems that the hurdles are just getting higher.
Years of consultation with human rights experts, global corporations, local communities and government officials finally led to the development of the UN Guiding Principles on Business and Human Rights (UNGPs). Thousands of stakeholders worldwide agree: human rights due diligence and providing access to remedies are core responsibilities of businesses. Great. Now what?
The Tomorrow’s Value Rating 2013 (TVR) an annual study conducted by DNV Two Tomorrows, underlines the difficulties of moving from agreement to execution. Over half of the assessed companies support the UNGPs, but they are unclear about how they actually implement them.
One difficulty in moving the agenda forward is the challenge of agreeing what constitutes good human rights performance, and how this is understood at a collective or industry level. This discussion is a crucial next step in understanding the practical applicability of the UNGPs. The TVR found that progress is slow, and we are still far from where we want to be.
For example, in the oil and gas sector only three of the 10 companies covered have a standalone human rights policy and management of human rights appears to be often reactive rather than proactive. Whereas the UN was a good facilitator for defining the interface between business and human rights, perhaps we should look at other structures to enable the execution of the next, practical steps? The TVR identified two challenges that companies struggle with: sector-specific implementation, and local specificities.
via Guardian Sustainable Business Blog
Some background to the UNGPs, developed by Harvard professor John Ruggie can be found below: